Method for fabricating vacuum fixturing using granular media

ABSTRACT

A method for fabricating vacuum tooling is disclosed using porous granular media. A sheet of steel webbing is affixed to a frame. A plurality of layers of fiberglass is affixed to the webbing. A vacuum port is installed through the webbing and plurality of layers of fiberglass. A granular media is mixed with epoxy to form a granular mixture. The granular mixture is layered over the plurality of layers of fiberglass to form a flat surface and machined for uniformity before sealing.

INCORPORATION BY REFERENCE TO ANY PRIORITY APPLICATIONS

Any and all applications for which a foreign or domestic priority claimis identified in the Application Data Sheet as filed with the presentapplication are hereby incorporated by reference under 37 CFR 1.57.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/913,616, entitled “METHOD FOR FABRICATING VACUUM FIXTURING USINGGRANULAR MEDIA” and filed on Mar. 6, 2018, which in turn is acontinuation of U.S. application Ser. No. 14/881,925, entitled “METHODFOR FABRICATING VACUUM FIXTURING USING GRANULAR MEDIA” and filed on Oct.13, 2015, which in turn claims the benefit of U.S. ProvisionalApplication No. 62/063,816, entitled “METHOD FOR FABRICATING VACUUMFIXTURING USING SINTERED MEDIA” and filed Oct. 14, 2014, the disclosuresof which are incorporated herein by reference.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to methods for holding thin metal and/orcomposite surfaces for machining, and, more particularly, to a methodfor making a vacuum tooling fixture from a porous granular material.

Current manufacturing demands faced by the aerospace industry requirethinner, stronger parts in order to meet constantly more demandingstandards for lowering costs, improving safety and increasing fuelmileage. As a result, manufacturers are faced with machining thin walledparts using high speed processes. Machining complex shapes with wallshaving thickness in the range of, for example, 0.010″ to 0.060″ (0.025to 0.15 cm). Such parts are prone to wander on a machining fixture whenbeing drilled or milled, for example.

Some have unsuccessfully tried to address this problem using vacuummethods including the use of materials like micro-balloons.Unfortunately, these materials are relatively costly and hard to shapeinto intricate parts. Because epoxy resin is typically used to bindround micro-balloons comprising such older materials it cannot easily beshaped or repaired if damaged. A significant drawback is that, sincesuch materials have inherently smooth surfaces, they do not preventslippage of many thin-walled parts while the parts are undergoingmachining.

The present invention provides a method for making vacuum toolingfixtures that solve the aforesaid problems. For the first time, tileinventors herein have discovered and developed a new and useful grittyand/or abrasive vacuum media that secures thin-walled parts in place formachining, that is easily repairable when damaged, and is low costcompared to prior methods and materials.

For example, in an advantage over previously available systems thevacuum media of the present invention is made of epoxy and gritty and/orabrasive granular material which may easily be formed and patched asdesired. Thus cuts or holes drilled into the granular media may berepaired as necessary for continued use.

BRIEF SUMMARY OF THE DISCLOSURE

This summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This summary is not intended to identify key features ofthe claimed subject matter, nor is it intended to be used as an aid indetermining the scope of the claimed subject matter.

In one embodiment a method for fabricating a vacuum table is disclosedusing porous granular media. A sheet of steel webbing is affixed to aframe. A plurality of layers of fiberglass is affixed to the webbing. Avacuum port is installed through the webbing and plurality of layers offiberglass. A granular media is mixed with epoxy to form a granularmixture. The granular mixture is layered over the plurality of layers offiberglass to form a flat surface and machined for uniformity beforesealing.

In one aspect the granular media consists essentially of sintered irongrit or epoxy resin.

In another aspect a course of spiral wrap tubing is encompassed by thegranular mixture.

In another aspect the course of spiral wrap tubing is configured in aserpentine pattern, a circular pattern, a branching pattern and/or anoval pattern.

In another aspect an additional stiffener is added between the granularmixture layer and the plurality of layers of fiberglass.

In another aspect the additional stiffener comprises a layer of balsawood and another layer of fiberglass.

In another aspect a tooling fixture with vacuum granular media isdisclosed including a pedestal and a part holding section attached atopthe pedestal. A vacuum port is coupled to the part holding section and afiberglass lining is applied to the inside of the part holding section.A porous granular media and epoxy mixture are positioned incommunication with the vacuum port. A urethane barrier seals the porousgranular media, and an O-ring groove is cut in the urethane barrier.

In yet another aspect of the invention, a method for vacuum forming ofthermally pliable parts using porous granular media is disclosed. Themethod includes:

providing a tooling fixture with porous granular media comprising:

-   -   a pedestal,    -   a part holding section attached atop the pedestal,    -   a vacuum port coupled to the part holding section,        a fiberglass lining applied to the inside of the part holding        section,    -   a porous granular media and epoxy mixture in communication with        the vacuum port,    -   a urethane barrier sealing the porous granular media, and    -   an O-ring groove in the urethane barrier;        thermally activating a part using a heating source;        removing the part from the heating source;        placing the part into the tooling fixture; and        conforming the part to the tooling fixture by applying vacuum        pressure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically shows a block diagram of a process for fabricatinga vacuum table using porous granular media.

FIG. 2 schematically shows an exploded cut-away side view of an exampleof a vacuum table made in accordance with the principles disclosedherein.

FIG. 2A schematically illustrates a cut-away side view of an example ofan assembled vacuum table with a vacuum tube attached.

FIG. 2B schematically illustrates a detail of a partial cut-away sideview of an example of the assembled vacuum table of FIG. 2A.

FIG. 3 schematically shows a top view of an example of an assembledvacuum table.

FIG. 4 schematically shows a top view of an example of expanded steelmesh material used in the assembly of a vacuum table.

FIG. 5 schematically shows an example of a tooling fixture made for usewith the vacuum granular media as disclosed herein.

FIG. 6 schematically illustrates a cut-away side view of an example of atooling fixture made for use with the vacuum granular media as disclosedherein.

FIG. 7 shows an example of a tooling fixture made with the vacuumgranular media as disclosed herein prior to machining the granularmaterial for the addition of the urethane layer.

FIG. 8 shows an example of a tooling fixture made with the vacuumgranular media as disclosed herein prior to machining the part holdingsection for the addition of the urethane layer.

FIG. 9 shows an example of the tooling fixture of FIG. 8 after additionof the urethane layer.

FIG. 10 shows a more detailed side view of an example of a toolingfixture of FIG. 6 made with the vacuum granular media as disclosedherein.

FIG. 11 schematically shows a block diagram of a process for vacuumforming of thermally pliable parts using porous granular media.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The examples presented herein are for the purpose of furthering anunderstanding of the invention. The examples are illustrative and theinvention is not limited to the example embodiments.

Unless the context requires otherwise, throughout the specification andclaims which follow, the word “comprise” and variations thereof, suchas, “comprises” and “comprising” are to be construed in an open,inclusive sense that is as “including, but not limited to.”

Reference throughout this specification to “one example” or “an exampleembodiment,” “one embodiment,” “an embodiment” or combinations and/orvariations of these terms means that a particular feature, structure orcharacteristic described in connection with the embodiment is includedin at least one embodiment of the present disclosure. Thus, theappearances of the phrases “in one embodiment” or “in an embodiment” invarious places throughout this specification are not necessarily allreferring to the same embodiment. Furthermore, the particular features,structures, or characteristics may be combined in any suitable manner inone or more embodiments.

Definitions

Generally, as used herein, the following terms have the followingmeanings unless the context suggests otherwise:

“Vacuum granular media” or “porous granular media” means any of grittynon-silica granular media including sintered iron, epoxy resin granulesand/or other irregularly-shaped, gritty and/or abrasive granularmaterial capable of transmitting a distributed vacuum force through alayer of the media having a thickness, for example, in the range ofabout 0.5 to about 2.0 inches. “Vacuum source” means a source forproviding a vacuum pressure of, for example, at least about 14.7 psi.

“Fluid communication” means connected to as to allow for pressure flowor air flow.

Vacuum Table with Granular Media

Referring now to FIG. 1, a block diagram of a process for fabricating avacuum table using porous granular media in accordance with theprinciples disclosed herein is schematically shown. A granular mediavacuum table has been made by the inventors according to the followingsteps:

At step 101 a frame is made from a framing material such as, forexample, steel in the shape of the table as desired. Usually the tableis a rectangular table wherein a plurality of sections of vacuumsurfaces may be installed. Hollow steel tubing may be advantageouslyemployed and cut to the lengths desired depending on the application.The tubing is welded together or otherwise attached to form the frame.

At step 104 a sheet of, for example, expanded steel webbing is tackwelded to the frame. Then, at step 106, a plurality of layers offiberglass are affixed epoxy to the steel webbing. For added strength,at step 108 an additional stiffener, such as, for example, a layer ofbalsa wood may be affixed to the top of the fiberglass and itselfcovered with another layer of fiberglass. A layer of epoxy may beaffixed to the bottom of the webbing at step 109 for added rigidity andstability.

At step 110 a course of spiral wrap tubing may optionally be affixed tothe top surface of the top fiberglass layer as, for example, by usinghot melt glue or an equivalent method. The course of spiral tubing isselected to disperse the vacuum according to the vacuum media surfacearea. For surface areas less than six inches square, spiral tubing maynot be needed. For larger areas the tubing may be advantageously laidout to form a serpentine pattern, a circular pattern, branching pattern,an oval or the like so as to distribute the vacuum force uniformly andform vacuum sections of about six square inches or less as a generalrule. When needed depending on the application, sections of commerciallyavailable spiral tubing of about ⅜ inch can be connected using Tconnectors or straight connectors. At step 111, or before the spiraltubing is applied, as is most convenient, a vacuum port is installed bycutting a suitable aperture through the laminated materials and adding aflange, pipe or other vacuum attachment mechanism to the bottom of thetable as shown herein below. The spiral tubing should be in fluidcommunication with the vacuum introduced through the vacuum tube that isthe vacuum is allowed to flow through the course of spiral tubing.

Then, at step 112, a mixed formulation of vacuum granular media isapplied over the spiral tubing to form the top surface of the vacuumtable. The layer of granular vacuum media is then applied over andcovers the spiral wrap tubing and the laminated surface. At step 114 thevacuum media surface is machined to a smooth, flat finish. At step 116the granular vacuum media is spray-painted to seal the surface andencapsulate small loose particulates.

Referring now to FIG. 2, an exploded cut-away side view of an example ofa vacuum table made in accordance with the principles disclosed hereinis schematically shown. A vacuum table 10 includes a top film 12, alayer of porous granular material 14, optional spiral tubing 16, anoptional layer of coated fiberglass 18, an optional layer of stiffener20, a plurality of layers of coated fiberglass 18, a tack-welded sheetof expanded steel webbing 24, a frame 26 and a bottom layer of epoxyresin 30 with filler for added stability.

Although the porous granular material may comprise various types ofmaterials, in one useful embodiment, the granular material comprises anon-silica abrasive in the form of a non-silica, fine abrasive blacksand available from Kleen Blast company located in Danville California.In one example a fine abrasive is rated at about 35 grit size. Suchabrasives are commonly used for sand blasting and may comprise sinterediron. Another useful type of abrasive is finally crushed walnut shellhowever, this has the drawback of absorbing moisture and is also heatsensitive. The granular vacuum media may advantageously be composed ofgeneral-purpose epoxy and abrasive. The ratio of epoxy to sand in oneexample is about 8% epoxy to about 92% abrasive. One useful type ofepoxy is made by Dura technologies. 80 LS-25AT, thixed. In one usefulembodiment, the fiberglass used to laminate the table comprises 20 ouncewoven fiber glass cloth which is commercially available. The top film 12may comprise any useful sealer such as spray paint, 30 epoxy and thelike. To ensure penetration into the media the sealer may be appliedunder vacuum conditions.

In another useful example, the granular material may advantageouslycomprise an epoxy resin formed into granular particles. One example of amethod for making granulated particles from epoxy resin follows thesteps below:

-   -   1. Epoxy resin in liquid form is poured into a container to form        ¼″ sheets;    -   2. The sheets are allowed to harden;    -   3. The hardened sheets are broken into small pieces using a        hammer mill such as is used in commercial mining;    -   4. The pieces are milled down to about 0.060 to 0.100        thousandths of an inch or to about a 36 grit; and    -   5. The grit is mixed with liquid epoxy as described herein and        cast into a rough shape and then machined as desired.

One advantage of using the aforedescribed granular materials likesintered media and epoxy resin is that they do not absorb moisture andwill not swell when exposed to humid or damp environments.

Referring now to FIG. 2A, a cut-away side view of an example of anassembled vacuum table with a vacuum tube attached is schematicallyillustrated. During assembly, a vacuum hose or pipe 32 is inserted upthrough a hole 33 cut through the lamented surface. The hose 32 iscoupled to a vacuum source 36 as indicated by direction arrow 34 toallow the vacuum to suction air through the granular media 14. Any partresting on the surface of the granular media will be held in place bythe suction and the gritty surface of the granular media.

Referring now to FIG. 2B, a detail of a partial cut-away side view of anexample of the assembled vacuum table of FIG. 2A is schematicallyillustrated. Aluminum or steel plates 200 may be used to brace thevacuum table components during final assembly. The edges of the toplayers of paint 12 and granular media 14 may be machined away to providea channel 203 around 30 the vacuum table. A layer of urethane 202 ispoured into the channel 203 to form a buffer around the perimeter of thevacuum table or a vacuum table section as the case may be. An O-ringgroove is cut, molded or milled into the urethane layer and an O-ring 80is affixed inside the O-ring groove to provide a vacuum seal with anyflat surface placed on the vacuum table when activated by powering on acoupled vacuum source 36. The urethane layer may itself include an edgethat advantageously protrudes above the surface of the coated granularmedia to provide a buffer or edge for tooling plates or the like whenbeing located on the table for machining.

Referring now to FIG. 3, a top view of an example of an assembled vacuumtable is schematically shown. This example includes a plurality ofvacuum sections 40 separated by a barrier, such as a layer of urethane202. Each of the vacuum surfaces are milled to a flatness in the samehorizontal plane as the others and coated as described above. Each ofthe vacuum surfaces will also be separately and directly coupled to oneor more vacuum sources (as shown above). Each vacuum section 40 may besurrounded by 15 interior 202A and exterior urethane barriers 202B. Theexterior urethane barrier 202B may uniformly protrude above each vacuumsurface 40 to allow tooling plates to be positioned onto the surfaceusing it as a mechanical guide or block. A plurality of O-rings 80 areinstalled in the urethane barriers to seal the perimeter of each vacuumsurface 40. While four vacuum surfaces are shown, those skilled in theart having the benefit of this disclosure will recognize that the numberof surfaces incorporated into a vacuum table can vary as is desired.

In a useful embodiment the vacuum sections 40 together with the exteriorand interior urethane barriers may be constructed to have a standardizedsurface area to match the size of standard tooling plates. For example,the vacuum sections may be sized to accommodate 12×12 inch, 12×24 inchor 24×24 inch plates and so on as desired.

Referring now to FIG. 4, a top view of an example of expanded steel meshmaterial used in the assembly of a vacuum table is schematically shown.The expanded steel sheet 24 is formed of webbing 25 and is commerciallyavailable in various thicknesses. Also shown is the frame 26 constructedof, for example, hollow steel tubes. In some embodiments other materialsmay be substituted for the expanded steel webbing. These may includewebbing or mesh made from steel, plastic, nylon, polyethylene, aluminum,composites, metal and combinations thereof.

Tooling Fixture with Granular Media

Referring now to FIG. 5, an example of a tooling fixture made for usewith the vacuum granular media as disclosed herein is schematicallyshown. A tooling fixture 50 includes a pedestal 52, a part holder 54, avacuum port 56 and a base 58. The pedestal 52 and part holding section54 are machined from a commercially available block closed-cellpolystyrene foam such as the trademarked brand Styrofoam®. In oneembodiment foam rated at 3.5 lb. per ft³ density was employed. Infabricating the tooling fixture the foam block is cut generally in theshape of the part to be held for machining with extra room for thevacuum media to be applied. After cutting the block into shape, afiberglass lining 60 is applied to the inside of the part holdingsection 54. The interior 61 comprises a machined section of granularmedia and epoxy mixture 14 located 20 below an O-ring groove 64 abovewhich is cut into a layer of urethane 202. A machining slot 63 is cutinto the part holder 54 to accommodate cutting tool operations. This isdescribed in more detail below. Depending on the application othermachining holes 51 may be included in the tooling fixture. In someexamples a spring loaded locating pin 67 may be affixed to the toolingfixture.

In one useful embodiment the base 58 may be made from a three-quarterinch IC six aluminum tooling plate. Other materials may also be usedsuch as fiberglass, laminates and the like. The top of the plate isground smooth and flat and an elongated bonding epoxy is applied forbonding the pedestal to the plate. The pedestal may advantageously bemade oversized for stability. It is put on the base and positioned on avacuum table. Once the tooling fixture 50 is in place on the table, thevacuum is activated thereby holding the fixture and (not shown) part inplace.

Referring now to FIG. 6, a cut-away side view of an example of a toolingfixture made with the vacuum granular media as disclosed herein isschematically illustrated. After cutting a slot through the middle ofthe tooling fixture, a vacuum tube 70, such as a ¾ inch flexible vacuumtube is inserted into the pedestal up to an outlet port 56 cut throughthe foam block and the fiberglass liner 60. A small groove sized forinserting a sealing ring (commonly called an O-ring) 64 is cut into theurethane layer 202 for tightly sealing the part holding section 54 whena vacuum is applied. The O-ring groove 64 will be cut into the shape ofthe perimeter of the (not shown) part to be machined. After the vacuumtube is installed the slot may be refilled with or packed with foamblock material.

Referring now to FIG. 7, an example of a tooling fixture made with thevacuum granular media as disclosed herein prior to machining thegranular material. This tooling fixture is shown at the stage afterinstalling the fiberglass liner and packing in the granular material,but prior to adding the urethane layer. Note that the granular material14 is packed with extra thickness so that it can set and be machineddown to form channels for the urethane layer to be added later. Thetooling fixture 500 includes a pedestal 520, a part holding section 540,and a vacuum port 560. For illustrative purposes slots 542 have beenleft uncovered to show where the foam block was cut for the purposes ofinstalling the vacuum tube as shown in FIG. 6, for example.

Referring now to FIG. 8, an example of a tooling fixture made with thevacuum granular media as disclosed herein prior to machining the partholding section for the addition of the urethane layer is shown. Here apartially fabricated tooling fixture 800 includes a part holding section854 which is still undergoing shaping. A channel 812 has been milledaround the part holding section 854 by removing granular materialpreviously packed into the section as described above. Some foammaterial 820 remains in the cavity. The channel 812 is partially coveredby tape or other means of damming so that urethane material can bepoured into the cavity.

Referring now to FIG. 9, an example of the tooling fixture of FIG. 8after addition of the urethane layer by first milling out some of thegranular material is shown. This will be followed by further machiningof both surfaces into the final part holding shape and to introduce anO-ring seal. The urethane layer 202 is added to the channel andsurrounds the granular media 14 to provide further stability and vacuumintegrity to the tooling fixture.

Referring now to FIG. 10, a more detailed side view of an example of atooling fixture made with the vacuum granular media as disclosed hereinis schematically illustrated. An O-ring groove 64 is cut into theurethane layer 202 and the mixture of the granular media with epoxy 14is shaped to fill the part holding section 54. The mixture is machinedto conform to the part to be machined up to the urethane layer. In usean O-ring 80 is inserted into the O-ring groove 64 so that when the partto be machined is inserted it cover and will be held against the O-ringby an applied vacuum to form a vacuum seal. The combination of theurethane layer, O-ring, the granular media and the vacuum will hold athin part tightly in place while being machined due to the grittyholding properties of the granular material.

Vacuum Forming Thermally Pliable Parts

Referring now to FIG. 11, a block diagram of a process for vacuumforming of thermally pliable parts using porous granular media isschematically shown. Using the vacuum tooling methods described above,thermally pliable parts may be formed. At step 1101 the part isthermally activated according to 25 known methods and made ready forforming. At step 1104 the part is removed from a heating source, placedinto the vacuum tool and formed into the desired shape. The vacuum toolmay be made with granular media in accordance with the methods describedherein. Then, at step 1106 a vacuum is applied through the granularmedia to pull the part into the desired shape against the vacuum toolingfixture. At step 1108 the part may be machined and trimmed as necessary.

The invention has been described herein in considerable detail in orderto comply with the Patent Statutes and to provide those skilled in theart with the information needed to apply the novel principles of thepresent invention, and to construct and use such exemplary andspecialized components as are required. However, it is to be understoodthat the invention may be carried out by specifically differentequipment, and devices and reconstruction algorithms, and that variousmodifications, both as to the equipment details and operatingprocedures, may be accomplished without departing from the true spiritand scope of the present invention.

What is claimed is:
 1. A vacuum tool for use in machining parts, thevacuum tool comprising: a tool frame defining a perimeter of the vacuumtool, the tool frame forming a cavity; a porous granular materialpositioned at least partially within the cavity, the porous granularmaterial comprising: a binding material; and an abrasive granularmaterial suspended in the binding material; a vacuum port in fluidcommunication with the porous granular material and configured tofacilitate passage of a vacuum pressure through the porous granularmaterial; and a physical seal surrounding at least a portion of theporous granular material, wherein the physical seal is configured tocontact a part to be machined, and wherein contact between the seal andthe part forms a vacuum seal between the tool frame and the part whenvacuum pressure is passed through the porous granular material.
 2. Thevacuum tool of claim 1, wherein the physical seal comprises anelastomer.
 3. The vacuum tool of claim 1, wherein the physical sealcomprises an 0-ring positioned partially within a groove surrounding atleast a portion of the porous granular material.
 4. The vacuum tool ofclaim 1, wherein the physical seal comprises an elastically resilientmembrane.
 5. The vacuum tool of claim 1, wherein the binding material isliquid epoxy configured to harden when cured.
 6. The vacuum tool ofclaim 1, wherein the abrasive granular material comprises one or moreof: a fine abrasive rated at about 35 grit size; hardened epoxy;sintered iron; or sintered iron.
 7. The vacuum tool of claim 1, whereinthe abrasive granular material comprises non-silica, fine abrasive sand.8. The vacuum tool of claim 1, wherein the binding material and abrasivegranular material inhibit absorption of moisture.
 9. The vacuum tool ofclaim 1, wherein a ratio of the binding material to the abrasivegranular material is about 8% binding material to about 92% abrasivegranular material.
 10. The vacuum tool of claim 1, wherein the physicalseal is arranged to define at least two separate sealing sections, eachsealing section comprising a portion of the porous granular materialsurrounded by a portion of the physical seal.
 11. A vacuum toolingfixture for use in machining parts, the vacuum tooling fixturecomprising: a part holder comprising: a porous granular material; and aphysical seal surrounding at least a portion of the porous granularmaterial; and a vacuum port in fluid communication with the porousgranular material and configured to facilitate passage of a vacuumpressure through the porous granular material, wherein the porousgranular material and the physical seal are sized and shaped to matewith an irregularly-shaped part to be machined, wherein the physicalseal is configured to contact the irregularly-shaped part, and whereincontact between the physical seal and the irregularly-shaped part formsa vacuum seal between the physical seal and the irregularly-shaped partwhen vacuum pressure is passed through the porous granular material. 12.The vacuum tooling fixture of claim 11, wherein the part holder includesan interior portion in which the porous granular material is positioned.13. The vacuum tooling fixture of claim 11, wherein the porous granularmaterial is sized and shaped to have a non-planar surface onto which thepart is mated.
 14. The vacuum tooling fixture of claim 11, furthercomprising a pedestal connected to the part holder, wherein the vacuumport is in fluid communication with a vacuum tube, and wherein thevacuum tube extends through at least a portion of the pedestal.
 15. Thevacuum tooling fixture of claim 11, further comprising a pedestalconnected to the part holder and a base connected to the pedestal. 16.The vacuum tooling fixture of claim 11, wherein the part holder isformed from a closed-cell polystyrene.
 17. The vacuum tooling fixture ofclaim 11, wherein the porous granular material comprises: a bindingmaterial; and an abrasive granular material suspended in the bindingmaterial, wherein a ratio of the binding material to the abrasivegranular material is about 8% binding material to about 92% abrasivegranular material.
 18. A vacuum tool assembly for use in machiningparts, the vacuum tool assembly comprising: a vacuum tool comprising: atool frame defining a perimeter of the vacuum tool, the tool frameincluding a cavity; a first porous granular material positioned at leastpartially within the cavity and comprising: a binding material; and anabrasive granular material suspended in the binding material; a firstvacuum port in fluid communication with the first porous granularmaterial and configured to facilitate passage of a vacuum pressurethrough the first porous granular material; and a first physical sealsurrounding at least a portion of the first porous granular material;and a vacuum tooling fixture connected to the vacuum tool, the vacuumtooling fixture comprising: a part holder comprising: a second porousgranular material; and a second physical seal surrounding at least aportion of the second porous granular material; and a second vacuum portin fluid communication with the second porous granular material andconfigured to facilitate passage of a vacuum pressure through the secondporous granular material, wherein the second porous granular materialand the second physical seal are sized and shaped to mate with a part tobe machined, wherein the second physical seal is configured to contactthe part, and wherein contact between the second physical seal and thepart forms a vacuum seal between the second physical seal and the partwhen vacuum pressure is passed through the second porous granularmaterial.
 19. The vacuum tool assembly of claim 18, wherein the firstporous granular material and second porous granular material are formedfrom a same binding material and a same abrasive granular material. 20.The vacuum tool assembly of claim 18, wherein the second vacuum port ispositioned above the vacuum tool.
 21. The vacuum tool assembly of claim18, wherein the abrasive granular material comprises one or more of: afine abrasive rated at about 35 grit size; hardened epoxy; sinterediron; or silica based granular media.
 22. The vacuum tool assembly ofclaim 18, wherein the abrasive granular material comprises a non-silica,fine abrasive sand.
 23. The vacuum tool assembly of claim 18, whereinthe vacuum tooling fixture further comprises a base connected to thepart holder, wherein the base is configured to contact the firstphysical seal to fix the base to the vacuum table.